1. Field of the Invention
The present invention relates to display of computer generated models and more specifically to rapid display of computer generated surfaces.
2. Description of Related Art
Computer graphic simulation methods typically create a computer generated model of objects or structures desired to be examined. These models are comprised of a number of surfaces. The surfaces can be approximated by a number of interconnected polygons, most probably triangles. These may be referred to as `polygonal models`. The polygonal models may be generated by conventional CAD/CAM methods or from volume data as described in the "marching cubes" method of U.S. Pat. 4,710,876 "System and Method for the Display of Surface Structures Contained Within the Interior Region of a Solid Body" by Harvey E. Cline and William E. Lorensen issued Dec. 1, 1987, assigned to the present assignee and hereby incorporated by reference. The volume data obtained from imaging systems such as Magnetic Resonant Imaging (MRI), Computed Axial Tomography (CAT), Positron Emission Tomography (PET), etc. is converted into lists of polygons for display on a graphics workstation.
Each of these triangles (identified by its vertices and possibly a vector normal to the surface of the triangle) are stored to be manipulated and displayed. These models may be manipulated by rotating them and displaying portions of the models. Transformations of coordinates are used to rotate the model with a 4.times.4 matrix equation. After transformation, the transformed model is displayed. Since all vertices of each polygon must be displayed in order to display the model, a great deal of processing power is required to rapidly manipulate and display each model.
Currently there is a need for a more efficient method of storing and displaying polygonal models.